feat: Application prototype (#14)

Creates a prototype user interface for dyna3 in the `app-proto` folder. The interface is dynamically constructed using [Sycamore](https://sycamore.dev).

The prototype includes:

  * An application state model (the `AppState` type)
    * A constraint problem model (the `Assembly` type), used in the application state
  * Two views
    * A 3D rendering of the assembly (the `Display` component)
    * A list of elements and constraints (the `Outline` component)

The following features confirm that the views can reflect and send input to the model:

  * You can select elements by clicking and shift-clicking them in the outline. The selected elements are highlighted in the display.
  * You can add elements using a button above the outline. The new elements appear in the display.

Co-authored-by: Aaron Fenyes <aaron.fenyes@fareycircles.ooo>
Reviewed-on: glen/dyna3#14
Co-authored-by: Vectornaut <vectornaut@nobody@nowhere.net>
Co-committed-by: Vectornaut <vectornaut@nobody@nowhere.net>

app-proto/Cargo.toml

@@ -0,0 +1,42 @@
+[package]
+name = "sketch-outline"
+version = "0.1.0"
+authors = ["Aaron"]
+edition = "2021"
+
+[features]
+default = ["console_error_panic_hook"]
+
+[dependencies]
+itertools = "0.13.0"
+js-sys = "0.3.70"
+nalgebra = "0.33.0"
+rustc-hash = "2.0.0"
+slab = "0.4.9"
+sycamore = "0.9.0-beta.3"
+
+# The `console_error_panic_hook` crate provides better debugging of panics by
+# logging them with `console.error`. This is great for development, but requires
+# all the `std::fmt` and `std::panicking` infrastructure, so isn't great for
+# code size when deploying.
+console_error_panic_hook = { version = "0.1.7", optional = true }
+
+[dependencies.web-sys]
+version = "0.3.69"
+features = [
+  'HtmlCanvasElement',
+  'Performance',
+  'WebGl2RenderingContext',
+  'WebGlBuffer',
+  'WebGlProgram',
+  'WebGlShader',
+  'WebGlUniformLocation',
+  'WebGlVertexArrayObject'
+]
+
+[dev-dependencies]
+wasm-bindgen-test = "0.3.34"
+
+[profile.release]
+opt-level = "s" # optimize for small code size
+debug = true # include debug symbols